Improper shutdown of system / Fragmentation Problems / Boot logs

Bill Moran wmoran at
Wed Jun 9 11:37:07 PDT 2004

Randy Pratt <rpratt1950 at> wrote:

> On Wed, 9 Jun 2004 07:05:43 +0800
> Robert Storey <y2kbug at> wrote:
> > 
> > > I am kinda new to FBSD, still kinda learning stuff. Anyway, when my
> > > system boots i see all kinda fragmentation information. How do I
> > > correct this? Any good reading material? 
> > 
> > FreeBSD will defragment itself without any action from the user.
> > However, defragmentation requires some blank space, and (ideally) you
> > should not let any partition get more than 80% full. You can check on
> > that with "df -h":
> I've been running partitions well over 90% for over six years on
> FreeBSD and have not seen any problems with doing so.
> Do you have a FreeBSD documentation reference for that 80% figure?

man tunefs

See, in particular, the section on the -m option, which describes (in brief)
the known performance problems and how FreeBSD reacts.

Robert's numbers aren't quite right.  The point at which performance starts to
suck is 90% full.

You won't have any _problems_, it's just that performance will degrade,
according to the man page, up to 3x slower.

Bill Moran
Potential Technologies

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